I. Field of the Invention
This invention relates generally to devices for translating a radial force into axial motion and/or force and more particularly to a helical ramp with a bearing and/or bearing surface in the center for transforming a radial force to axial movement.
II. Discussion of the Prior Art
Most latches, clamps and jacks have a lever with a linear motion moving in the same direction as the object to be moved. The leverage obtained depends on the lever length. These devices are frequently not easy to use because the lever moves toward the object leaving very little room to maneuver and frequency limiting the length of the lever.
Many latches, clamps and jacks have more than one moving part which increases the cost of making and assembling the device. These devices have several parts with pivot points with one part inserted into and pivoting thereon. These multiple parts are subject to wearing out and breaking.
A lever arm that moves radially and translates an object axially is preferred in some applications. By using ramps sliding on each other there are no moving parts to assemble and no assembled parts to break.
A pair of opposing helical ramps are used for translating an object axially when the ramps are rotated relative to each other. A handle on one ramp when moved radially turns the ramp such that it slides up or down on the opposing static ramp to translate an object axially.
Upper and lower cams both have at least one opposing ramp surface such that they slide on each other. No levers having pivot points and connections therefore are used. A bearing on one cam extends into a bore on the other cam so that the helical ramps move concentrically.
The ramps have walls which prevent the ramps from being radially translated past the ends of the ramps. The ramps also have three dimensional sine wave portions which nest with each other to limit rotation and provide a locking position which takes some force to overcome.
A locking pin can be inserted into a bore through both the upper and lower cams to ensure that the cams will not rotate relative to each other. A locking pin member having two arms can fit over the lever on the upper cam. The locking pin member may have apertures for inserting a safety pin ensuring the locking pin cannot be removed from the handle, or a lock can be used through the apertures on the arms of the locking pin member, for security, ensuring the locking pin can not be removed.
A shaft through the center of the upper and lower cams can be attached to an object temporarily by inserting one end into a coupler, or the shaft can be permanently attached to an object. The upper cam receives the shaft and, with a threaded shaft, the usable length of the shaft can be adjusted by treading a nut on the shaft.
In some embodiments a pair of ratchets on the shaft allows multiple turns of the handle to raise or lower an object.
One embodiment of the invention uses a bar through an aperture on the lower cam member. The lower cam member is thereby fixed in position such that it cannot rotate. The upper cam rotates by use of the handle. The bar is moved upward or downward when the handle is translated. One use is for securing a snowmobile to a trailer. The shaft is inserted into a coupler on the trailer, the bar is placed over the skis on the snowmobile. The adjustment nut is threaded onto the shaft that runs through the center of the lower and upper cam for a tight fit of the bar on the snowmobile skis when the handle is rotated to the locking position such that the cams apply an axial force on the bar extending over the snowmobile skis, securing the snowmobiles to the trailer they are being transported on.
It is an object of the invention to provide a means for quickly clamping one object to another.
It is an object of the invention to raise or lower objects.
It is an object of the invention to convert a radial force to an axial force.
It is an object of the invention to secure an object from moving.
It is an object of the invention to extend and retract a pair of cams by using helical ramps.
It is an object of the invention to secure a snowmobile on a trailer.
It is an object of the invention to provide a lockable clamp to secure objects.
It is an object of the invention to provide a stop for the cams to prevent rotation beyond a portion of a revolution either clockwise or counterclockwise.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.